Hydraulic impact tool



Jan. 6, 1953 Q F, WARREN 2,624,177'

HYDRAULIC IMPACT TOOL Filed Feb. 8, 1945 SSheets-Sheet l FWZ@ a? l' 35 I riff/gi 7 -f/@f ff?! f :H 6m f Z/ Z Z /9 5 i a.; 4g

C. F. WARREN HYDRAULIC IMPACT TOOL Jan. 6, 1953 3 Sheets-Sheet 2 Filed Feb. 8, 1945 3 Sheets-Sheet 5 Filed Feb. a, 1,945

,FIZ f LQ if Patented Jan. 6, 1953 HYDRAULIC IMPACT TOOL Charles F. Warren,

Warren, deceased,

executrix o assignor to Charles F. Warren, Jr.

Milwaukee, Wis.; Kathleen f said Charles F. Warren,

Application February 8, 1945, Serial No. 576,767

(Cl. (S-54.5)

11 Claims.

This invention relates to a driving mechanism designed for transmitting a series of blows to percussively actuated tools, and it is particularly concerned with the type of apparatus in which the tool driving impulses are transmitted v:from a power driven pump through a liquid column acting against a rigid reciprocating plunger which operates as a hammer against thhe tool.

One object of the invention is to provide a new and improved impact tool for the purpose indicated.

Another object of the invention is to provide an impact tool of improved design in which an air spring or air cushion is employed to assist the return strokes of the driving plunger.

yIt is also an object ci the invention to provide an impact tool actuated by a pre-loaded column of liquid and having a quantity oi trapped air serving as a return spring which is placed initially under precompression and automatically replenished as needed during operation of the tool.

More specifically the invention includes a cylinder with a piston therein and a driving plunger smaller than the piston and rigidly extending therefrom through one end of the cylinder in air-tight relation thereto so that a quantity of air is trapped in the chamber between the piston and that end of the cylinder to serve as a cushion or air spring for assisting the return stroke of the plunger, together with hydraulic driving means extending from the other side of the piston through the other end portion of the cylinder for actuating the piston and the plunger, and means for automatically replenishing the trapped air at substantially atmospheric pressure in the event of leakage or loss of a portion thereof.

Other objects and advantages of the invention will appear from the following description taken in connection with the drawings in Which:

Fig. l is a front elevation of an impact tool embodying this invention.

Fig. 2 is a sideelevation of Fig. 3 is a top plan View of said tool.

Fig. i is a substantially axial vertical section taken as indicated at line 4-4 on Fig. 2 and on a larger scale, its impulse generator means being shown on a reduced scale.

Fig. 5 is a side elevation of a tool embodying a modiiication of the invention.

Fig. 6 is a top plan view of the same with one of the handles broken away.

Fig. 7 is a fragmentary side elevation of the the same.

2 lower portion of the tool illustrating the steel retainer.

Fig. 8 is a vertical axial section taken substantially as indicated at line 8--8 on Fig. 5.

Fig. 9 is a fragmentary vertical section taken as indicated at line 9-9 on Fig 8 and on a larger scale.

Fig. 10 is a plan section taken as indicated at line IB-IU on Fig. 8 showing the fluid control valve in closed position.

Fig. 11 is a plan sectional View similar to Fig. 10 but showing the valve at open position.

Fig. 12 is a fragmentary detail section showing an alternative location of a check valve.

While there are illustrated in the drawings and will hereinafter be descrbed in detail a preferred embodiment of the invention and certain modiiications thereof, it is to be understood that the invention is not limited. to the particular forms illustrated, but that on the contrary it is contemplated that various changes and rearrangements may be made by those skilled in the art without departing from the scope of the invention as deined in the appended claims.

The devices illustrating this invention are shown herein equipped with pointed steels indicated in each instance at A as of the type adapted for drilling or breaking concrete structures or pavements, and for like work, but it may be understood that the hammers and driving mechanisms oi these devices may be employed forv various other purposes and with other steels, each adapted to its own class of work. As shown in Fig. 1, the driving mechanism includes a casing I which 'comprises a cylinder 2 and a cylindrical guide portion 3 extending from the lowerl end thereof. A cross bar type of handle is shown at 4 extending from a portion 5 which connects the handle with the head '6 of the cylinder 2 and, as indicated in Fig. 4, this connecting portion 5 serves as a valve chamber for a valve controlling the operation of the reciprocating column of liquid through which power is transmitted to the tool or steel A in apparatus of this type. A fragment of the conduit through which the liquid column acts is shown at 'I and may be under@ stood as extending from a suitable'pumping device such as that shown and described in Patent No. 2,397,174; granted March 26, 1946, so asv to he embodied in a system of the type disclosed in U. S. Letters Patent Re. 22,122 dated June 16, 1942. The mechanisms of said patents include means for keeping the liquid column pre-loaded at a predetermined pressure to insure that it :shall act as a rigid element in transmitting rapid reciprocation to the hammer or other tool which it operates.

As shown in Fig. Ll, the cylinder 2 is provided with a liner sleeve 3 tted between a packing washer or gasket 9 at its lower end and the depending skirt i!! of the cylinder head 6 which engages the upper end of the sleeve 8. The guide portion 3 of the casing I includes a guide bore provided with a liner sleeve or bushing II of smaller diameter than the interior of the cylinder 2 and the driving plunger i2 is fitted slidably in the sleeve I I being provided with a hammer head I3 preferably having circumferential grooves with packing rings Iii therein. The upper end of the driving plunger i2 carries rigidly a piston I which may be integral with the plunger I2, if desired, and which is also circumferentially grooved to receive packing rings I6. Thus, the space or chamber I'I between the piston i5 and the lower end wall I 8 of the cylinder 2 is substantiially air-tight, and the air trapped therein is adapted to serve as a cushion or spring for returning the plunger l2 upwardly after each downward driving stroke thereof. Eventually, however, the repeated compression of the air in the space I'I will result in some loss or leakage past the packing rings i@ or the rings i6, and to provide for the constant replacement of this loss the cylinder 2 is formed with an air admission port I9 which is positioned to be uncovered by the piston I5 at the upper limit of its normal stroke so that momentarily the space il is placed in communication with the outer atmosphere, whereby any deficiency of air in the lower end of the cylinder will be supplied by atmospheric air entering port I 9 to be trapped beneath the piston I5 as the piston moves downwardly in its next power stroke. The opposite end of the cylinder is also in communication with the outer atmosphere through a relief port 2I to avoid compression of the air in the space 2Q to such an extent as to retard or impair the operation of the plunger I2.

The plunger l2 is actuated by means of the hydraulically operated piston 22 which is shown in the form of a rod considerably smaller in diameter than the air piston I5. The piston 22 fits snugly and slidably in an elongated bushing 23 secured in the cylinder head 5 and depending therefrom into the cylinder 2. At its lower end the piston 22 impinges upon a slug 24 of hardened steel pressed into the piston I 5 so that the reciprocationof the piston 22 is transmitted directly to the plunger I2, and although the reciprocations of the liquid column acting through the conduit 'I are quite rapid, the pre-loading of the column, as explained in said Patent 2,397,174, and Letters Patent Re. 22,122 insures that cone tact between the piston 22 and the plunger I2 will be maintained throughout the driving and return strokes of the plunger; this precompression of the liquid in the system results in a precompression of the air in the chamber Il, suicient to force the piston l5 approximately to the position indicated at m on Fig. 4. During its working stroke the piston will travel slightly farther, to the position denoted at y, and the return stroke will carry it upward to the point marked e, at which the air inlet port I9 is un covered by the piston.

The fluid controlling valve is in the form of a hollow cylinder 25 having a single oblong port 26 adapted to be registered with a like port 2'I of a bushing 28 which is secured iXedly in the cylindrical bore of the connecting portion 5 between the cylinder head 6 and the handle 4. The bushing 28 is so positioned that its port 21 provides communication with the inlet passage 29 into which the conduit 'I is coupled by its threaded terminal 30. The lower end of the bushing 28 rests upon a shoulder 3i of the valve chamber and the bushing is secured in place by a threaded gland 32 clamped against its upper end with suitable packing 33 interposed. The valve member 25 is formed with a central stem 35 extending through a bore in the gland 32 and provided with suitable packing rings 34 to render it fluid-tight. The upper end of the stem 35 is squared, as seen in Fig. 3, and carries an operating lever 35 which is held normally in valve closing position by means of a spring 3l, but which is disposed where it is easily accessible to the thumb of the operators right hand while grasping the handle 4 so that operation of the tool itself is under the control of the operator at all times. When the handle 35 is swung to position for registering the port 2K5 with the port 2 the reciprocations of the uid column in the conduit 'I are transmitted to the piston 22, it being understood that the passage 29 and the space within the hollow valve member 25 are already lled with liquid constituting an extension of the conduit in the column I. The movements of the column originating in the pumping device, hereinafter described, produce rapid reciprocation of the piston 22 and corresponding movement of the plunger I2 with its hammer head I3 whereby rapidly repeated impacts are delivered to the upper end of the steel A while its lower end is held in contact with the material to be worked upon.

The shank of the steel A is guided somewhat loosely in a bushing 11E secured in the lower end of the guide 3 and when the tool is lifted away from the work the steel is prevented from falling out of the bushing d@ by means of a retainer 6I which engages a shoulder 62 formed on the steel A. The retainer 4I is shown as composed of a pair of spring arms wththeir upper end portions secured in position by a screw 43 engaged in the wall of the guide portion 3 of the casing and having a reduced inner end portion 44 which serves to anchor the bushing 45 therein. The spring members are disposed between parallel flanges i5 projecting from the side of the guide cylinder 3 and additional securement is provided in the form of a cleat 4E which extends under the head of the screw 43 and is clamped against the retainer springs by screws 41. The lower ends of the springs are bent toward the steel A and may be arcuately notched to iit around the body of the tool at oneside to insure engagement with the shoulder 42 when the steel A is lowered out of operative engagement with the hammer head i3. At'operative position the retainer M rests against the iiat side of a cam member d3 journaled in the guide cylinder 3 and to release the steel A it is only necessary to rotate the cam through a limited angle by means of its lever arm 4S swinging the latter to the position illustrated in Fig. 1 and thus bringing the lower end of the retainer 5I out of the path of the shoulder 42. The pumping or impulse generating device more particularly shown in said Patent2,39'7,174 comprises a casing ISG providing in a iioor portion a sump I QI for a liquid in which the hydraulic column is constituted. The power drive shaft Iii carries a cam iii-3 which reciprocates the differentially diarnetered piston |84 in cylinder I O5 and cylinder ISt. The piston is urged toward the' cam-by a heavyi compression spring. H11.v The pipe which carries the hydraulic column from the .impulse generating device to the tool communicates with cylinder H16.

Adjacent the shoulder |68 which provides a working face for piston |04 is an annular channel with which communicates the check valvecontrolled intake pipe |59 from the sump. This piston supplies makeup liquid to replenish system losses. The makeup liquid displaced by the piston face |08 passes check valve H0 into conduit III to displace a spring-loaded piston valve H2 to permit excess liquid to escape under pressure through port H3 back to the sump. The compression of spring H4 is adjustable to predetermine the pressure at which makeup liquid Will he admitted to duct H5 into cylinder |85 behind the smaller end of piston |54 in the advanced position of the latter.

The modied structure shown in Figs. 5 to l1 operates on the same principles as that already described, but differs in detail therefrom. The casing 5l includes a cylinder 52l and a cylindrical guide portion 53, together with a cross bar handle 54 secured between lugs 55 which project from the cylinder head 56. The actuating column of liquid is enclosed in a conduit 51 shown entering the cylinder head 56 at one side and communieating with a valve chamber 58 which is formed in the cylinder head. The shank of the steel A projects into the guideway 5i in which the plunger 52 is mounted for reciprocation with a hammer head 63 at its lower end. The latter is provided lwith packing rings 64 and the upper end of the plunger 52 carries the piston B5 having packing rings EE so that the air space E1 between the piston 55 and the lower end of the cylinder 52 will be substantially air-tight. The piston 65 Ais shown provided with a check valve 68 normally seated by spring 55 but adapted to open toward the space 61 for admitting air thereto so as to replace any loss or leakage of air and maintain a sufficient quantity therein to serve as a pneumatic spring or cushion to assist in the return of the plunger 52 after each of the driving strokes. .The space above the piston 55 in the cylinder 52 is provided with a relatively large port 1l which affords constant communication with the atmosphere and maintains a supply of; air from which the air in the space 61 may be replenished through the check valve 6B duringthe return stroke of the plunger 62.

Insteadof a metallic piston like that of the structure already described the presentiorm, as shown in jFig. 8, includes a tube 12 communicating withithe valve chamber 58 at its upper end and at its lower end telescopically engaged in a bushing 13 set into the piston 55. The bore in the piston 65 which accommodates the bushing 13 extends through the plunger 52, lthe reduced end of the hammer 63' being secured in the lower end-of said bore. The bushing 13 is made long enough to insure a substantially fluid-tight slidable connection with the tube 12 and a spacer sleeve 14 is disposed between the lower end of the bushing 13 and the reduced end oi the hammer head E3, said sleeve 14 having a slightly larger bore than the bushingv 13. This insures easy working clearance for reciprocation of the plunger 52 in response to reciprocation of the column of liquid extending through the tube 12 and sleeve 14 into contact with the upper or inner end oi the hammer head B3. Thus, when the valve in the valve chamber 53 is open the movements of the column of liquid in the consage in the tube 12.

duit '51 actuaire the plunger` s2 and deliver rapidly .repeated hammer blows against the upper- The valve in the chamber 58 consists of twin gate members 15, 15 attached by pivots 16 to the upper face -of a plate 11 having a central port 18 therein which registers with thel pas-- A pair of links 19 are connected respectively to the va1ve members 15 by pivots and the opposite ends of said links are connected together by a pivot 8i so that they form a toggle. A plunger 82 mounted in a guide bushing 83 is arranged with its head 84 in contact with the connected ends of the links 19 so that, as seen in Fig. 11, inward movement of the plunger 82 swings the valve gates 15 to open position at which they uncover the port 18 thus placing the column oi fluid from the tube 12 in operative communication with the column in the conduit 51 so that movements ofthe latter will be transmitted to the plunger 62 and its hammer head 63. A bent spring member 85 embracing the valve members 15 urges them yieldingly to closed position and serves to close them whenever pressure on the outer end of the plunger 82 is relieved.. For opening the valve such pressure is applied by means of a hand lever 86 pivotally mounted in a slot in one end of the handle 54 and having a depending arm 81 which engages the end of theA plunger 82. The openend of the steel ing movement of the gates or valve members 15 is limited by stop pins plate 11.

The steel retainer for holding the tool member A in position is shown in Fig. 8 as a dog 90 pivoted at 9i between lugs 92 formed on the side of the guide cylinder 53. vThe tail portion 53 of the dog 9D is shown engaging the concentric portion of the cam 94 which is also pivoted in the lugs 92v but by swinging the lever arm 95 of the cam its flat portion 95 may be brought opposite the tail 93 of latter to be swung clear of the shoulder 42 on the steel A so that the from the guide bushing der 5.3.

As shown in Fig. 12 instead of mounting the check valve 68 in the piston 65, 68a may be provided in a fitting 68o secured in the side wall of the cylinder 52 and affording access to the space 61 below the piston 65. This arrangement `will render the check valve somewhat more accessible ii it should lrequire cleaning or other servicing.

Itl will vbe understood that when an impact toolef either form herein-described is employed in a hydraulic impact transmitting system of 88 upstanding from the said Letters-Patent Re. 22,122 and with a pump' like that; above described. and shown moreparticularly in Patent 2,397,174, the pre-loadingunit l. In a high speed reciprocable fluid-operated tool, a rst cylinder, a rst pistonY therein.- a tool driving plunger connected with the lpiston the dog 90 permitting thesteel 'may be removed- 91 of the guide cylinthe check valve-- the return strokes ofv and extending from one end of the piston through one end of the cylinder in bearing relation to the cylinder, whereby air trapped between the end of the first cylinder and the iirst piston provides a pneumatic spring for returning the plunger and the iirst piston from their driving stroke, and hydraulic driving means for said first piston comprising a second cylinder and a second displacement piston of materially smaller cross section than the rst piston and hydraulic impulse connections to said second cylinder; said second piston having means connecting it with the rst piston, said means having a portion of materially smaller cross sectional area than the first piston and extending through the end of the iirst cylinder, the space between the first piston and the end of the first cylinder about said means being in open communication with the atmosphere, said iirst cylinder having an opening of suiiicient capacity so that air trapped behind the first piston can escape without substantial obstruction, thereby permitting the free piston return by the trapped air constituting said pneumatic spring.

2. The device of claim 1 in further combination with means for automatically replacing leakage of air from the space about said piston connecting means between said first piston and iirst cylinder for maintaining in such space a sufficient volume of air to serve effectively as a pneumatic spring.

3. The device of claim 2 in which the means for automatically replacing air leakage comprises a port with which said first cylinder is provided in its side wall in a position rto be uncovered by said irst piston as said first piston approaches its extreme retracted position.

4. In a uid operated tool, a cylinder, a piston therein, a tool driving plunger rigid with the piston and extending from one end of the cyling der in substantially air-tight relation thereto, whereby the air in the space between said end of the cylinder and the piston provides a pneumatic spring for returning the plunger from its driving stroke, means automatically replacing leakage of air from said space, a second piston of smaller diameter than the rst extending slidably through the other end of the cylinder in Huid-tight relation thereto, a hydraulic pressure chamber surmounting said end of the cylinder, one end of said smaller piston being exposed to the pressure in said chamber and the other end engaging the iirst piston, the other end of the cylinder having a port communicating with the atmosphere and of sufncient capacity to pass air freely from about the smaller piston, whereby to facilitate the rapid reciprocation of said piston and plunger subject alternately to pressure in said chamber and to said pneumatic spring.

5. In a uid operated tool, a cylinder, a piston therein, a tool driving plunger rigid with the piston and extending from one end of the cylinder in substantially air-tight relation thereto, whereby the air in the space between said end of the cylinder and the piston provides a pneumatic spring for returning the plunger from its driving stroke, a second piston of smaller diameter than the rst extending slidably through the other end of the cylinder in fluid-tight relation thereto, a hydraulic pressure chamber surmounting said end of the cylinder, one end of said smaller piston being reciprocable in said pressure chamber in response to reciprocation of the fluid therein and the other end engaging the iirst pisducing pump having er rigid with said air turning the plunger from its impact ton, the said other end of the cylinder having a port communicating substantially directly to the atmosphere and of suiicient capacity to permit substantially unimpeded reciprocation of the piston and plunger.

6. In the combination deiined in claim 5, a pair of telescoped cylindrical valve members deiining said pressure chamber and having ports adapted to be registered, one of said members being xed and the other rotatable for effecting registration of said ports, the innermost of said members constituting a chamber in which the second piston is reciprocable, and a pressure uid supply conduit opening laterally into said chamber by way of said ports when they are registered.

7. The device of claim 6 in which the innermost member is rotatable and has an end wall with a stem extending therefrom, in further combination with a pair of handle bars extending from opposite sides of the pressure chamber, and said inner valve member and extending alongside one of said handle bars.

8. In a fluid operated tool, a casing, a tool driving plunger and a piston bothrmounted for reciprocation in the casing with one end of the piston operatively engaged with the plunger, the casing including a hydraulic pressure chamber constituting a cylinder for said piston and in which the other end of the piston is exposed, a pair of sleeves deiining said pressure chamber, said sleeves being telescopically engaged and having ports adapted to be registered, one of said sleeves being adjustable relatively to the other for effecting registration of said ports, a pressure fluid supply passage opening laterally into said chamber through said ports to provide force for the driving strokes of the piston and plunger, and resilient means acting thereon in the opposite direction, said piston telescoping into the inner sleeve in its return strokes.

9. In a hydraulic impact transmitting system which includes a conduit confining a rigid, reciprocable column of liquid with an impulse proa cylinder and a piston of said conduit and means column under a predetera fluid operated tool having a work delivering piston closing the other end of the conduit, an air compressing piston of materially greater diameter than the work delivering piston and in pressure transmitting connection therewith, a cylinder in which the latter piston reciprocates, an impact delivering plungcompressing piston and extending from one end of its cylinder in substantially air-tight relation thereto, whereby the air in the space between said end of the cylinder and said piston provides a pneumatic spring for restroke, and means automatically replacing leakage of air from said space, the end of the last cylinder behind the air compressing piston having a vent opening communicating with the atmosphere and having sufficient capacity to pass air without substantial obstruction to permit the free return of the air compressing piston in response to the reaction of said pneumatic spring.

10. In a hydraulic impact transmitting system which includes a conduit conning a rigid, re-

therein closing one end maintaining the liquid mined initial pressure:

maintaining the liquid column under a predetermined initial pre-loading pressure: a uid operated tool comprising a work delivering piston closing the other end of the conduit, an air compressing piston of materially greater diameter than the work delivering piston and in pressure transmitting connection therewith, a cylinder in which the latter piston reciprocates, an impact delivering plunger rigid with said air compressing piston and of smaller diameter and extending from one end of said last-mentioned cylinder in substantially air-tight relation thereto, the initial pre-loading of the liquid column placing the air under pre-compression in the space between said end of said cylinder and the piston therein, providing resilient means for returning the plunger from its impact stroke, and said last mentioned cylinder having a port comprising means automatically exposing said space to atmospheric pressure during the return strokes of the plunger for replacing leakage of air from said space, the end of the last mentioned cylinder behind the air compressing piston having a vent opening communicating with the atmosphere and having sufcient capacity to pass air without substantial obstruction to permit the free return of the air compressing piston in response to the reaction of said pneumatic spring.

11. In a hydraulic impact transmitting system which includes a conduit conning a rigid, reciprocable column of liquid with an impulse producing pump having a cylinder and a piston therein closing one end of said conduit and means maintaining the liquid column under a predetermined initial pre-loading pressure: a fluid operated tool comprising a work delivering piston closing the other end of the conduit, an air compressing piston of materially greater diameter than the work delivering piston and in pressure transmitting connection therewith, a cylinder in which the latter piston reciprocates, an impact delivering plunger rigid with said air compressing piston and of smaller diameter and extending from one end of said last-mentioned cylinder in substantially air-tight relation thereto, the initial pre-loading of the liquid column placing the air under pre-compression in the space between said end of said cylinder and the piston therein, providing resilient means for returning the plunger from its impact stroke, said last mentioned cylinder having a port through which air is admitted to said space during the return stroke of the plunger to replace leakage and maintain a uniform quantity of air in said space subject to the pressure of the liquid column, the end of the last mentioned cylinder behind the air compressing piston having a vent opening communicating with the atmosphere and having sufiicient capacity to pass air without substantial obstruction to permit the free return of the air compressing piston in response to the reaction of said pneumatic spring.

CHARLES F. WARREN.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 489,757 Reilly Jan. 10, 1893 722,179 Keller Mar. 3, 1903 872,885 Anderson Dec. 3, 1907 1,494,030 Slater May 13, 1924 1,771,672 Degenhardt July 29, 1930 1,857,624 Degenhardt May 10, 1932 1,938,860 Renfer Dec. 12, 1933 1,969,798 Hultquist Aug. 14, 1934 2,168,806 Reilly Aug. 8, 1939 2,260,268 Warren et al Oct. 21, 1941 2,397,174 Warren et al Mar. 26, 1946 2,429,390 Case Oct. 21, 1947 FOREIGN PATENTS Number Country Date 389,318 Great Britain Mar. 16, 1933 

